Picture rotated in web page, normal in file?

What happened? I have a normal picture in a file, and when I grabbed it and set it in the web page, it rotated sideways to the left. I even reduced the size to make sure its not a sizing issue. Small picture rotated sideways. What did I do, or how do you fix it? Are these kind of bugs common in programing?

Thanks Jay. I'm kinda new at this. I placed it in the head after creating the style css and it didn't change anything. Can you expand on this and also how to differentiate rotating one picture and not the other?